feat: 1080p60 NVENC selfbot broadcast (8 Mbps default)

Bump the default broadcast to 1080p 60fps at 8 Mbps and route both encode
stages through the GPU (RTX 5050, h264_nvenc) so 60fps stays smooth without
loading the 4-core host.

- selfbot.ts: capture ffmpeg uses h264_nvenc when streamHw is on (falls back
  to software x264 otherwise), and prepareStream now passes Encoders.nvenc()
  so the library's transcode runs on the GPU too. Guard loadLib for Encoders.
- config.ts: VNC_FRAMERATE default 30 -> 60, VNC_BITRATE_KBPS 4000 -> 8000.
- .env.example: document the new 1080p60/8 Mbps defaults and STREAM_HW.

Verified locally: h264_nvenc x11grab holds a steady 60fps with headroom,
Encoders.nvenc() returns valid h264_nvenc settings, and tsc --noEmit passes.
Live Discord voice-channel verification pending a host reboot.

bot/src/stream/selfbot.ts

@@ -46,9 +46,9 @@ export class SelfbotStreamer implements ScreenStreamer {
           `원본 오류: ${(e as Error).message}`,
       );
     }
-    if (!vs.Streamer || !vs.prepareStream || !vs.playStream) {
+    if (!vs.Streamer || !vs.prepareStream || !vs.playStream || !vs.Encoders) {
       throw new Error(
-        "@dank074/discord-video-stream v6 API(Streamer/prepareStream/playStream)를 찾지 못했습니다. " +
+        "@dank074/discord-video-stream v6 API(Streamer/prepareStream/playStream/Encoders)를 찾지 못했습니다. " +
           "package.json 버전을 ^6.0.0으로 맞추세요.",
       );
     }
@@ -64,7 +64,7 @@ export class SelfbotStreamer implements ScreenStreamer {
       return "셀프봇 송출은 음성 채널 안에서 호출해야 합니다.";
     }
     const { selfbot, vs } = await this.loadLib();
-    const { Streamer, prepareStream, playStream } = vs;
+    const { Streamer, prepareStream, playStream, Encoders } = vs;
 
     this.streamer = new Streamer(new selfbot.Client());
     await this.streamer.client.login(this.config.selfbotToken);
@@ -77,13 +77,22 @@ export class SelfbotStreamer implements ScreenStreamer {
     // x11grab), then pipe that stream into the library. Relying on the lib's
     // bundled libav for the x11grab input device is not portable; piping the
     // system ffmpeg is. (Verified live against a real voice channel.)
+    //
+    // With streamHw on (default) the capture is encoded by the GPU
+    // (h264_nvenc, RTX 5050) so 1080p60 stays smooth without loading the CPU;
+    // the library then transcodes with NVENC too (see encoder below). Without
+    // hardware support we fall back to software x264.
+    const hw = this.config.streamHw;
+    const captureCodecArgs = hw
+      ? ["-c:v", "h264_nvenc", "-preset", "p4", "-tune", "ll"]
+      : ["-c:v", "libx264", "-preset", "ultrafast", "-tune", "zerolatency"];
     const capture = spawn("ffmpeg", [
       "-loglevel", "error",
       "-f", "x11grab",
       "-framerate", String(this.config.vncFramerate),
       "-video_size", this.config.vncResolution,
       "-i", this.config.vncDisplay,
-      "-c:v", "libx264", "-preset", "ultrafast", "-tune", "zerolatency",
+      ...captureCodecArgs,
       "-pix_fmt", "yuv420p", "-g", String(this.config.vncFramerate),
       "-f", "mpegts", "pipe:1",
     ]);
@@ -101,6 +110,7 @@ export class SelfbotStreamer implements ScreenStreamer {
         videoCodec: "H264",
         bitrateVideo: this.config.vncBitrateKbps,
         bitrateVideoMax: Math.round(this.config.vncBitrateKbps * 1.5),
+        encoder: hw ? Encoders.nvenc() : Encoders.software(),
       },
       this.controller.signal,
     );